Electromagnetic indicator operated by coil and permanent magnet means

ABSTRACT

Electromagnetic indicator is provided which comprises electromechanical means for positively retaining the same in the reset condition, and electromagnetic means and biasing means for respectively releasing the said electromechanical retaining means and placing the indicator in the set condition. Included are indicating means which provide readily discernible indicia that the indicator is in the set condition.

0 United States Patent 1151 3,636,55t Pihl 1451 Jan. 18, 1972 [s41 ELECTROMAGNETIC INDICATOR 2,388,448 11 1945 Sundt ..340/37 OPERATED BY COIL AND 2,434,870 1/1948 Solovieff..... ...340/373 J PERMANENT MAGNET MEANS 2,866,186 12/1958 Hardesty.. ...340/373 1 2,393,901 1/1946 Haigh ...340/376) 2] nt George Pihl, Abington, Mass- 2,408,106 9/1946 Stearn ..340/371 [73] Assignee: General Time corpomfion, Stamford 2,444,476 7/1948 Steam ..340/376 Conn Primary Examiner-Harold l. Pitts [22] Filed: May 20, 1969 Au0meyDean S. Edmonds, Willis H. Taylor, Jr. and R. Mor 21 Appl. No.: 826,248 Adams [57] ABSTRACT [52] US. Cl ..340/373, 340/366, 3344(g/33786l, Electromagnetic indicator is provided which comprises elec [51] Int Cl Gosh 5/22 Gosh 5/26 tromechanical means for positively retaining the same in the [58] Fie'ld "5 381 376 reset condition, and electromagnetic means and biasing mean: for respectively releasing the said electromechanical retaining 5 6] References Cited means and placing the indicator in the set condition. Include: are indicating means which provide readily discernible indiciz UNITED STATES PATENTS that the indicator is in the set condition.

2,314,122 3/1943 Bruno ..340/373 5 Claims, 3 Drawing Figures ELECTROMAGNETIC INDICATOR OPERATED BY COIL AND PERMANENT MAGNET MEANS BACKGROUND OF THE INVENTION This invention relates to a new and improved electromagnetic indicator and, more particularly, to a miniature electromagnetic indicator which provides for positive electromechanical latching thereof in the reset condition.

As is believed well known by those skilled in this art, electromagnetic indicators providing nonilluminated contrasting color indicia find utility in a variety of installations, e.g., aircraft, portable electronic equipment, etc., and are preferred over illuminated indicators such as those using glow tubes or bulbs where the ambient light conditions make it difficult to distinguish the display from the surrounding background. Electromagnetic indicators also are preferred for installations that are subject to shock or where changes in ambient temperature are large enough to accelerate deterioration of glow tubes and the like. Thus, and although a wide variety of electromagnetic indicators are known in this art, it may be understood that, in general, such electromagnetic indicators are either unduly complex and expensive, cannot be readily fabricated in miniaturized form, do not provide for positive electromechanical latching in the reset condition thereof, and/or do not provide indicia which can readily be sensed both visually and by feel.

OBJECTS OF THE INVENTION It is, accordingly, an object of this invention to provide a new and improved electromagnetic indicator which is of relatively simple design and construction, and of relatively low cost, and which can readily be fabricated in miniaturized form.

Another object of this invention is the provision of an electromagnetic indicator as above which provides for positive electromechanical latching in the reset condition thereof, through the simple use of permanent magnet means, to thus greatly inhibit indicator malfunction.

Another object of this invention is the provision of an electromagnetic indicator as above providing indicia which can readily be sensed visually and/or by feel.

A further object of this invention is the provision of an electromagnetic indicator as above which requires the use of only readily available components of proven dependability in the fabrication thereof to provide for long periods of reliable operation thereof.

A still further object of this invention is the provision of an electromagnetic indicator as above which is particularly, though not exclusively, adapted for circuit fault indication function in conjunction with airborne computer systems or the like.

SUMMARY OF THE INVENTION As currently preferred, the new and improved electromagnetic indicator of the invention comprises connected armature means and an indicator button which are movable from first positions thereof, when the indicator is in the reset condition, to second positions thereof when the indicator is in the set condition. Electromechanical latching means, including first and second permanent magnet means, are provided to retain the armature means and indicating button in said first positions thereof, and electromagnetic means and biasing means are provided to respectively release said electromechanical latching means and move said armature means and said indicating button to said second positions thereof. Said indicating button is arranged to be flush with the indicator housing means when in said first position thereof and to project therefrom when in said second position thereof, and indicia are formed on said indicating means which are visible only when the same are in said second position thereof to provide readily discernible visual indication that the indicator has assumed the set condition.

The above and other objects and advantages of the inven tion are believed made clear by the following detailed descrip tion thereof taken in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of electromagnetic indicato1 means constructed in accordance with the teachings of the in vention and depicts the same in each of the reset and set con ditions thereof, respectively,

FIG. 2 is a cross-sectional view taken substantially along line 2-2 in FIG. 1 and depicts the electromagnetic indicator means in the condition thereof immediately upon circuit faul detection and attendant indicator means coil energization and FIG. 3 is a cross-sectional view taken along line 33 in FIG 2.

Referring initially to FIG. 1, it may be seen that electromagnetic indicators, each of which is constructed and operative ir accordance with the teachings of this invention, are generally indicated at 10 and 12, respectively, and it may be understooc that indicator 10 is depicted in the reset condition thereo while indicator 12 is depicted in the set condition thereof.

The electromagnetic indicators 10 and 12 are mounted, in a manner described in detail hereinbelow, from a panel 14 S( that the respective end faces 16 and 18 of the indicators an substantially flush with the panel surface. Each of the elec tromagnetic indicators 10 and 12 includes an indicating but ton, as shown at 20 and 22, respectively, and it may be un derstood that with the electromagnetic indicator of the inven tion in the reset condition thereof, as illustrated by indicato 10, the indicating button 20 will be substantially flush with lht indicator end face 16 while, with the electromagnetic indica tor of the invention in the set condition thereof, as illustrater by indicator 12, the indicating button 22 will be moved to pro ject beyond the indicator end face 18 to provide indication which may be sensed visually and/or by feel, of this indicato: condition.

Referring now to FIG. 2, the indicator 10 may be seen tr comprise a generally boxlike housing 24 which is constructet from any suitably nonmagnetic and nonconductive material it the nature, for example, of plastic. Preferably, the housing 2 includes one wall thereof, as indicated at 26 in FIG. 3, which i: removable therefrom in the manner of a cover to enable in dicator assembly.

Permanent magnets 28 and 30, respectively polarized as in dicated in FIG. 2, are disposed as shown adjacent oppositr housing walls and may be supported therefrom by a suitabl potting compound as indicated at 32 and 34.

A generally L-shaped upper core member 36 of any suita ble, readily magnetizable material in the nature of soft iron i disposed as shown in surface contact with the lower surface 0 the permanent magnet 28 and includes a downwardly extend ing leg portion 38, while a generally U"-shaped lower con member 40, again of any suitable, readily magnetizablt material is disposed as shown in surface contact with the lowe permanent magnet 30 and includes upwardly extending le positions 42 and 44. If desired, the respective core member 36 and 42 are cemented to the respective permanent magnet 28 and 30 at the areas of the surface contact therebetween This adjacent placement of the respective permanent magnet 28 and 30, and the upper and lower core members 36 and 31 may, in any event, be understood to be effective to polariz the latter as indicated in FIG. 2.

A coil assembly is indicated generally at 46 and may be see: to include a bobbin 48 of any low-friction, suitably nonmag netic and nonconductive material in the nature, for example of DuPonts Teflon, about which is wound a coil 50 of suitabl insulated fine wire. Preferably, the coil 40 is insulated from the respective core members 36 and 50, as by a winding 52 o a Teflon tape which is wound as shown around the said coil.

n aperture 54 which may, for example, be of generally angular cross section, is formed in the bobbin 48 to extend ethrough as shown generally centrally thereof. he coil assembly 46 is preferably maintained in the deed position thereof within the housing 24 by the disposiof any suitable potting compound, as indicated at 56 and a FIG. 3, in the spaces therebetween.

tabbing board assembly is indicated at 60 and may be I to include a generally centrally disposed aperture 62 red therein and into which the respective core member leg ions 38 and 44 extend. ibs 64 and 66 are formed to extend inwardly as shown I one housing end wall 68 to cooperate with the adjacent ing board assembly portions in the definition of housing spaces. Two relatively stifi wire leads 70 and 72 extend as vn through the rear housing wall and through the said end :es into suitable connection with conductive lands on the ing board assembly 60, and the said end spaces are then 1 with any suitable potting compound as indicated at 74 76. s best seen in FIG. 3, one end of the coil assembly 46 ex- .s into contact with the tabbing board assembly 60, and it be understood that the nonillustrated coil ends are My connected, as by soldering, to the said conductive s of the fonner to provide for energization of the said coil mbly through energization of the wire leads 70 and 72. n outer bushing is indicated at 80 and is mounted from the :r housing end wall 82, as through the use of the completally shaped, stepped end wall and bushing portions as inted at 84 and 86, respectively, to extend as shown outlly of the said end wall in such manner that the bore 88 of bushing 80 is in general alignment with, although substany larger than, the aperture 54 of the bobbin 48. The phery of the outer bushing 80 may be threaded, as inted at 90, for indicator mounting purposes as described in .il hereinbelow.

generally cup-shaped bearing 91, again of any suitable, friction material in the nature of DuPonts Teflon, is osed as shown with the outer bushing 80 and may be untood to be maintained therewithin in any convenient ner as, for example, through cementing. n armature assembly is generally indicated at 92 and may een to comprise a soft iron armature 94 which extends as vn longitudinally of the bobbin bore 54. The armature 94 ides a step member 96 which is welded as shown to one amity thereof. Further included in the armature assembly l a shaft 98 which extends as shown through the bearing 91 is movable therethrough generally longitudinally of the r bushing 80. A yoke 100 is formed at one extremity of :haft 98 and a pin 102 may be seen to extend through the yoke, and through a somewhat oversized bore 104 formed e adjacent portion of the armature 96, to somewhat looselnnect the said armature to the said shaft. illustrated in FIGS. 2 and 3, the indicating button may sen to be generally cup shaped, and to include a bushing disposed therewithin and affixed thereto in any conent manner as, for example, through cementing or presslg. The other extremity of the armature assembly shaft 98 nds as shown in tight-fitting manner into the bushing 106, lay alternatively be cemented thereto, to, in any event, re the said indicating button to the said shaft extremity for one purpose.

somewhat compressed coil spring 108 is disposed as m around a portion of the shaft 98 between the opposed lCBS of the bearing member 91 and the bushing 106 actively, and may thus be readily understood to be effecto bias the indicating button outwardly of the outer bushl0. A gasket 110 is disposed as shown within the bearing ber 91 around the shaft 98 to inhibit the travel of ture to within the housing 24. In addition, a gasket 111 is )sed as shown around the shaft 98 between the outer face l6 bearing 91 and the coil spring 108 to further inhibit ture travel to within the housing 24.

Mounting of the electromagnetic indicator of the invention in mounting means in the nature of panel 14 may, of course, be readily effected by the provision of a complementally threaded bore in the latter and the threading and tightening of the threaded peripheral portion of the outer bushing thereinto, from behind the panel, as should be obvious. Of course, a wide variety of other and different indicator-mounting means may be utilized and may, for example, comprise the use of means which are complementally threaded with respect to outer bushing 80 and may cooperate therewith to draw the housing 24 into tight contact with the rear surface of the panel 14.

OPERATION In operation, for use for example in indicating a circuit condition such as a fault in electrical equipment in the nature of airborne electrical equipment, it may be understood that the electromagnetic indicator of the invention would be mounted as above in an instrument panel of the aircraft, and the wire leads 70 and 72 suitably connected to an equipment computer or coordinating system which is effective to accumulate data and generate a pulse for the momentary energization of the said leads upon the occurrence of a fault. For such use it may be understood that the generally convex end surface 112 of the indicating button 20, and the end face 16 of the outer bushing 80, would preferably be colored the same, substantially nonreflective black as would the face of the instrument panel 14 to blend therewith, while the peripheral side surface 114 of the said indicating button would preferably be colored in a contrasting, bright and substantially reflective white.

Under normal operating conditions, that is to say prior to fault detection and attendant indicator lead energization, the indicating button 20 would be in the reset condition thereof as depicted in FIGS. 2 and 3, and for indicator 10 in FIG. 1, wherein the end face 112 of the indicating button would be maintained substantially flush with the end face 16 of the outer bushing 80 and the surface of instrument panel 14.

More specifically, it may be understood that the indicating button 20 would be retained in this position, against the bias of the somewhat compressed coil spring 108, by the latching effect of the contact between the step member 96 and the upper core member leg portion 38 as clearly illustrated in FIG. 2, and the described connections between the armature 94, the shaft 98 and the said indicator button. Since armature 94 is, under these conditions given a north polan'ty at the left-hand end thereof under the influence of the similarly polarized leg portions 42 and 44 of the lower core member 40, it may be understood that the end of the armature 94 which carries step member 96 will be attracted to the adjacent, and oppositely polarized, end of the upper core member leg portion 38 to electromechanically retain the armature in the latched position and positively prevent unintentional unlatching thereof under the force of environmental condition in the nature of excessive aircraft vibration.

Upon fault detection and attendant coil energization, however, it may be understood that the coil assembly 46 will be effective to magnetically polarize the armature 94 along its length as indicated thereon in FIG. 2 so that the step member end of the armature is repelled from upper core member leg portion 38 and attracted to lower core member leg portion 44, while the opposite armature end is repelled from lower core member leg portion 42.

As this occurs, the annature 94 will in essence pivot about the pin 102, due to the looseness of the connection therebetween, in such manner that the latch member 96 will be liberated from the upper core member leg portion 38 and will pass between the respective upper and lower core member leg portions 38 and 44 as the coil spring 108 pulls the armature assembly 92 to the right as seen in FIGS. 2 and 3 to pop the indicating button 20 out of the outer bushing 80, as indicated in phantom in FIG. 2 and as illustrated by the indicator 12 in FIG. 1, to expose the white-colored sides of the former and indicate the fault and the need for appropriate remedial action. As the indicator button 20 is popped out, the armature will simply slide part of the way through the aperture 54 of the bobbin 48 to assume a generally diagonal position therewithin, again as indicated in phantom in FIG. 2.

The electromagnetic indicator will, of course, remain in this set condition thereof under the effect of coil spring 10, despite the termination of the fault generated pulse and attendant coil deenergization, until such time as the indicator button 20 is detected, either by sight and/or by feel, and the electromagnetic indicator returned to the reset condition thereof by the simple manual pushing of the indicator button 20 back into the bore 88 of the outer bushing 80 to relatch the armature.

More specifically, and bearing in mind that the coil 50 is no longer energized, it may be understood that as travel of the armature 94 within the bobbin bore 54 back to the latched condition of the former is commenced, the right-hand portion of the armature 94 will be attracted to the lower core member leg portion 42 which, under the influence of the permanent magnet 30, will be effective to provide the armature 94 with a north pole at its left-hand end and an induced south pole at its point of contact therewith. As a result, and as the left-hand or step member end of the armature 94 passes between the respective upper and lower core member leg portions 38 and 44, it may be understood that the said armature end will be repelled by lower core member leg portion 44 and attracted to upper core member leg portion 38, whereupon the armature 94 will again pivot about pin 102, as described hereinabove, to return to the electromechanically latched position thereof with the relevant surfaces of step member 96 and upper core member leg portion 38 again retained in firm surface contact as depicted in FIG. 2.

To clearly illustrate the adaptability of the design of the electromagnetic indicator of the invention to miniaturized construction, it may be understood that a currently proposed form thereof has the overall dimensions of three-fourths inch by one-fourth inch by three-eighths inch, and weighs less than grams as completely assembled.

While I have shown and described the preferred embodi ment of my invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

What is claimed is:

1. An electromagnetic indicator having a reset condition, and being spring biased toward a set condition and indicia to indicate said conditions, an energizable coil, an armature in proximity to said coil, said armature being laterally movable with respect to the inner portion of said coil, an indicatin; member connected to said armature and movable therewith the improvement comprising:

a latch member on said armature,

a first permanent magnet polarized in one state to engagt said latch member to effect latching of said indicatin; member and armature in said reset condition, and

a second permanent magnet spaced from said first per manent magnet and polarized oppositely therefrom tt operate in conjunction with said energizable coil and sait first permanent magnet to disengage said latch membe and indicating member to said set condition upon ener gization of said coil.

2. An electromagnetic indicator as defined in claim 1, tht

improvement further comprising:

a magnetizable first core member magnetically couplet with said first permanent magnet;

a magnetizable second core member magnetically couplet with said second permanent magnet;

said armature located between said core members ant latchingly attracted to said first core member when sait indicating memberjs in said reset condition. 3. An electromagnetic indicator as defined in claim 1, tht

improvement further comprising:

a housing;

an end face forming part of said indicating member, sait end face substantially flush with said housing when sait indicating member is in said reset condition and project ing from said housing when said indicating member is i1 said set condition;

said indicating member when in said set condition having 1 side surface which is visible; and

indicia on said side surface to provide visual indication tha said indicating member is in said set condition.

4. An electromagnetic indicator as defined in claim 2, tht

improvement further comprising:

a leg on said first core member, and

a leg on said second core member, said leg on said first cor member effective to magnetically repel said armature ant said leg on said second core member effective to magneti cally attract said armature upon energization of said coi to unlatch said armature and permit said spring bias tt move said indicating member to set condition.

5. An electromagnetic indicator as defined in claim 2 i1 which said armature has an opening therein spaced from sait latch member;

a connecting element fixed to said indicating member ant loosely coupled to said armature at said opening to permi said armature to loosely pivot when moving between sait reset and set conditions. 

1. An electromagnetic indicator having a reset condition, and being spring biased toward a set condition and indicia to indicate said conditions, an energizable coil, an armature in proximity to said coil, said armature being laterally movablE with respect to the inner portion of said coil, an indicating member connected to said armature and movable therewith, the improvement comprising: a latch member on said armature, a first permanent magnet polarized in one state to engage said latch member to effect latching of said indicating member and armature in said reset condition, and a second permanent magnet spaced from said first permanent magnet and polarized oppositely therefrom to operate in conjunction with said energizable coil and said first permanent magnet to disengage said latch member and indicating member to said set condition upon energization of said coil.
 2. An electromagnetic indicator as defined in claim 1, the improvement further comprising: a magnetizable first core member magnetically coupled with said first permanent magnet; a magnetizable second core member magnetically coupled with said second permanent magnet; said armature located between said core members and latchingly attracted to said first core member when said indicating member is in said reset condition.
 3. An electromagnetic indicator as defined in claim 1, the improvement further comprising: a housing; an end face forming part of said indicating member, said end face substantially flush with said housing when said indicating member is in said reset condition and projecting from said housing when said indicating member is in said set condition; said indicating member when in said set condition having a side surface which is visible; and indicia on said side surface to provide visual indication that said indicating member is in said set condition.
 4. An electromagnetic indicator as defined in claim 2, the improvement further comprising: a leg on said first core member, and a leg on said second core member, said leg on said first core member effective to magnetically repel said armature and said leg on said second core member effective to magnetically attract said armature upon energization of said coil to unlatch said armature and permit said spring bias to move said indicating member to set condition.
 5. An electromagnetic indicator as defined in claim 2 in which said armature has an opening therein spaced from said latch member; a connecting element fixed to said indicating member and loosely coupled to said armature at said opening to permit said armature to loosely pivot when moving between said reset and set conditions. 